When exposed to polarized light, chromophores that have their absorption transition moments oriented along the electric vector of the incident light are preferentially excited. Hence the excited-state population is partially oriented along the electric vector of the polarized excitation light. The rotational diffusion of the fluorophores results in depolarization of the emitted light. The degree of anisotropy of the polarization of the emitted light is described by fluorescence anisotropy, \(r\)  [1]}, and is given by
\(r = \frac{I_{\parallel }-I_{\perp }}{I_{\parallel }+2I_{\perp }}\) 
